J.C. Penney CEO Marvin Ellison recently said that e-commerce companies' biggest challenge is that they are all expanding their businesses and pushing for faster delivery, but UPS, Fedex and especially the United States Postal Service aren't able to keep up, at least not at same cost that exists today, because they're not increasing their delivery capacity at the same rate e-commerce is growing, He said this will cause a supply and demand issue "that's going to be apparent here pretty soon."